Does the G3 come with a File Manager and more importantly if it does then does it support the MicroSD card and other Storage options (USB peripherals)?
As many will know Google removed in KitKat the option to copy and remove items from external storage unless they have write permissions.
Now Sony got round this problem by installing 'File Manager' on the Z2 and it has write permissions for accessing the MicroSD card.
It would be ludicrous if LG left out a File Manager with write permission for storage peripherals.
Your only option for access to the MicroSD card for writing, copying, deleting etc. then would be to root and not everyone wishes to do that.